1. Field
One embodiment of the invention relates to a head separated camera apparatus comprising a camera head and a camera control unit which controls the same, which are separated from each other.
2. Description of the Related Art
As well known, a head separated camera apparatus comprises a camera head and a camera control unit (CCU) as separate bodies. The camera head incorporates a solid-state imaging element, such as a CCD (charge coupled device) sensor or a CMOS (complementary metal-oxide semiconductor) sensor. The CCU supplies a driving control signal to the solid-state imaging element of the camera head, and processes a signal output from the solid-state imaging element to a video signal. The camera head and the CCU are connected to each other via a cable comprising a bundle of signal lines.
Generally, the head separated camera has been developed to, for example, inspect a small area where a human cannot enter. Therefore, the camera head is required to be as compact as possible with the fewest possible components. Further, the cable connecting the camera head and the CCU is required to be long.
The longer the cable in the head separated camera apparatus, the more the waveform disturbance and the attenuation of a signal including a video signal transmitted from the camera head to the CCU.
Jpn. Pat. Appln. KOKAI Publication No. 2000-349727 discloses a bidirectional transmitting apparatus comprising a camera head side transmitting device and a CCU side transmitting device, which are connected via a triax cable. In this apparatus, the CCD side transmitting device detects amplitude of a transmission signal transmitted from the camera head side transmitting device, calculates the attenuation of a signal in the triax cable, and determines the length of the triax cable based on the attenuation. Each of the camera head side transmitting device and the CCU side transmitting device include a gain variable amplifier. The gain variable amplifiers set optimum gains according to the cable length.